What types of water systems must comply with the standard?
The new standard will apply to all 54,000 community water systems. A community water system is a system that serves 15 locations or 25 residents year-round, including most cities and towns, apartment buildings, and mobile home parks with their own water supplies. EPA estimates that roughly five percent, or 3,000 community water systems serving 11 million people, will have to take corrective action to lower the current levels of arsenic in their drinking water. The revised standard will also apply to the 20,000 non-community water systems that serve at least 25 of the same people more than six months of the year, such as schools, churches, nursing homes, and factories. EPA estimates that five percent, or 1,100 of these water systems, serving approximately 2 million people, will need to take measures to meet the revised standard.
